linux-stable.git/arch/x86/kernel/setup.c, branch linux-rolling-lts

x86/kexec: add a sanity check on previous kernel's ima kexec buffer

2026-03-04T12:21:17+00:00

[ Upstream commit c5489d04337b47e93c0623e8145fcba3f5739efd ]

When the second-stage kernel is booted via kexec with a limiting command
line such as "mem=", the physical range that contains the carried
over IMA measurement list may fall outside the truncated RAM leading to a
kernel panic.

    BUG: unable to handle page fault for address: ffff97793ff47000
    RIP: ima_restore_measurement_list+0xdc/0x45a
    #PF: error_code(0x0000) – not-present page

Other architectures already validate the range with page_is_ram(), as done
in commit cbf9c4b9617b ("of: check previous kernel's ima-kexec-buffer
against memory bounds") do a similar check on x86.

Without carrying the measurement list across kexec, the attestation
would fail.

Link: https://lkml.kernel.org/r/20251231061609.907170-4-harshit.m.mogalapalli@oracle.com
Signed-off-by: Harshit Mogalapalli 
Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec")
Reported-by: Paul Webb 
Reviewed-by: Mimi Zohar 
Cc: Alexander Graf 
Cc: Ard Biesheuvel 
Cc: Baoquan He 
Cc: Borislav Betkov 
Cc: guoweikang 
Cc: Henry Willard 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Jiri Bohac 
Cc: Joel Granados 
Cc: Jonathan McDowell 
Cc: Mike Rapoport 
Cc: Sohil Mehta 
Cc: Sourabh Jain 
Cc: Thomas Gleinxer 
Cc: Yifei Liu 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

Merge tag 'mm-nonmm-stable-2025-08-03-12-47' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-08-03T23:23:09+00:00

Pull non-MM updates from Andrew Morton:
 "Significant patch series in this pull request:

   - "squashfs: Remove page->mapping references" (Matthew Wilcox) gets
     us closer to being able to remove page->mapping

   - "relayfs: misc changes" (Jason Xing) does some maintenance and
     minor feature addition work in relayfs

   - "kdump: crashkernel reservation from CMA" (Jiri Bohac) switches
     us from static preallocation of the kdump crashkernel's working
     memory over to dynamic allocation. So the difficulty of a-priori
     estimation of the second kernel's needs is removed and the first
     kernel obtains extra memory

   - "generalize panic_print's dump function to be used by other
     kernel parts" (Feng Tang) implements some consolidation and
     rationalization of the various ways in which a failing kernel
     splats information at the operator

* tag 'mm-nonmm-stable-2025-08-03-12-47' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (80 commits)
  tools/getdelays: add backward compatibility for taskstats version
  kho: add test for kexec handover
  delaytop: enhance error logging and add PSI feature description
  samples: Kconfig: fix spelling mistake "instancess" -> "instances"
  fat: fix too many log in fat_chain_add()
  scripts/spelling.txt: add notifer||notifier to spelling.txt
  xen/xenbus: fix typo "notifer"
  net: mvneta: fix typo "notifer"
  drm/xe: fix typo "notifer"
  cxl: mce: fix typo "notifer"
  KVM: x86: fix typo "notifer"
  MAINTAINERS: add maintainers for delaytop
  ucount: use atomic_long_try_cmpxchg() in atomic_long_inc_below()
  ucount: fix atomic_long_inc_below() argument type
  kexec: enable CMA based contiguous allocation
  stackdepot: make max number of pools boot-time configurable
  lib/xxhash: remove unused functions
  init/Kconfig: restore CONFIG_BROKEN help text
  lib/raid6: update recov_rvv.c zero page usage
  docs: update docs after introducing delaytop
  ...

x86: implement crashkernel cma reservation

2025-07-20T02:08:23+00:00

Implement the crashkernel CMA reservation for x86:
- enable parsing of the cma suffix by parse_crashkernel()
- reserve memory with reserve_crashkernel_cma()
- add the CMA-reserved ranges to the e820 map for the crash kernel
- exclude the CMA-reserved ranges from vmcore

Link: https://lkml.kernel.org/r/aEqp1LD2og4QeBw9@dwarf.suse.cz
Signed-off-by: Jiri Bohac 
Cc: Baoquan He 
Cc: Dave Young 
Cc: David Hildenbrand 
Cc: Donald Dutile 
Cc: Michal Hocko 
Cc: Philipp Rudo 
Cc: Pingfan Liu 
Cc: Tao Liu 
Cc: Vivek Goyal 
Signed-off-by: Andrew Morton

Add a new optional ",cma" suffix to the crashkernel= command line option

2025-07-20T02:08:22+00:00

Patch series "kdump: crashkernel reservation from CMA", v5.

This series implements a way to reserve additional crash kernel memory
using CMA.

Currently, all the memory for the crash kernel is not usable by the 1st
(production) kernel.  It is also unmapped so that it can't be corrupted by
the fault that will eventually trigger the crash.  This makes sense for
the memory actually used by the kexec-loaded crash kernel image and initrd
and the data prepared during the load (vmcoreinfo, ...).  However, the
reserved space needs to be much larger than that to provide enough
run-time memory for the crash kernel and the kdump userspace.  Estimating
the amount of memory to reserve is difficult.  Being too careful makes
kdump likely to end in OOM, being too generous takes even more memory from
the production system.  Also, the reservation only allows reserving a
single contiguous block (or two with the "low" suffix).  I've seen systems
where this fails because the physical memory is fragmented.

By reserving additional crashkernel memory from CMA, the main crashkernel
reservation can be just large enough to fit the kernel and initrd image,
minimizing the memory taken away from the production system.  Most of the
run-time memory for the crash kernel will be memory previously available
to userspace in the production system.  As this memory is no longer
wasted, the reservation can be done with a generous margin, making kdump
more reliable.  Kernel memory that we need to preserve for dumping is
normally not allocated from CMA, unless it is explicitly allocated as
movable.  Currently this is only the case for memory ballooning and zswap.
Such movable memory will be missing from the vmcore.  User data is
typically not dumped by makedumpfile.  When dumping of user data is
intended this new CMA reservation cannot be used.

There are five patches in this series:

The first adds a new ",cma" suffix to the recenly introduced generic
crashkernel parsing code.  parse_crashkernel() takes one more argument to
store the cma reservation size.

The second patch implements reserve_crashkernel_cma() which performs the
reservation.  If the requested size is not available in a single range,
multiple smaller ranges will be reserved.

The third patch updates Documentation/, explicitly mentioning the
potential DMA corruption of the CMA-reserved memory.

The fourth patch adds a short delay before booting the kdump kernel,
allowing pending DMA transfers to finish.

The fifth patch enables the functionality for x86 as a proof of
concept. There are just three things every arch needs to do:
- call reserve_crashkernel_cma()
- include the CMA-reserved ranges in the physical memory map
- exclude the CMA-reserved ranges from the memory available
  through /proc/vmcore by excluding them from the vmcoreinfo
  PT_LOAD ranges.

Adding other architectures is easy and I can do that as soon as this
series is merged.

With this series applied, specifying
	crashkernel=100M craskhernel=1G,cma
on the command line will make a standard crashkernel reservation
of 100M, where kexec will load the kernel and initrd.

An additional 1G will be reserved from CMA, still usable by the production
system.  The crash kernel will have 1.1G memory available.  The 100M can
be reliably predicted based on the size of the kernel and initrd.

The new cma suffix is completely optional. When no
crashkernel=size,cma is specified, everything works as before.


This patch (of 5):

Add a new cma_size parameter to parse_crashkernel().  When not NULL, call
__parse_crashkernel to parse the CMA reservation size from
"crashkernel=size,cma" and store it in cma_size.

Set cma_size to NULL in all calls to parse_crashkernel().

Link: https://lkml.kernel.org/r/aEqnxxfLZMllMC8I@dwarf.suse.cz
Link: https://lkml.kernel.org/r/aEqoQckgoTQNULnh@dwarf.suse.cz
Signed-off-by: Jiri Bohac 
Cc: Baoquan He 
Cc: Dave Young 
Cc: Donald Dutile 
Cc: Michal Hocko 
Cc: Philipp Rudo 
Cc: Pingfan Liu 
Cc: Tao Liu 
Cc: Vivek Goyal 
Cc: David Hildenbrand 
Signed-off-by: Andrew Morton

video: Make global edid_info depend on CONFIG_FIRMWARE_EDID

2025-06-16T09:00:29+00:00

Protect global edid_info behind CONFIG_FIRMWARE_EDID and remove
the config tests for CONFIG_X86. Makes edid_info available iff
its option has been enabled.

Signed-off-by: Thomas Zimmermann 
Reviewed-by: Helge Deller 
Link: https://lore.kernel.org/r/20250602075537.137759-3-tzimmermann@suse.de

Merge tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-05-31T22:44:16+00:00

Pull MM updates from Andrew Morton:

- "Add folio_mk_pte()" from Matthew Wilcox simplifies the act of
creating a pte which addresses the first page in a folio and reduces
the amount of plumbing which architecture must implement to provide
this.

- "Misc folio patches for 6.16" from Matthew Wilcox is a shower of
largely unrelated folio infrastructure changes which clean things up
and better prepare us for future work.

- "memory,x86,acpi: hotplug memory alignment advisement" from Gregory
Price adds early-init code to prevent x86 from leaving physical
memory unused when physical address regions are not aligned to memory
block size.

- "mm/compaction: allow more aggressive proactive compaction" from
Michal Clapinski provides some tuning of the (sadly, hard-coded (more
sadly, not auto-tuned)) thresholds for our invokation of proactive
compaction. In a simple test case, the reduction of a guest VM's
memory consumption was dramatic.

- "Minor cleanups and improvements to swap freeing code" from Kemeng
Shi provides some code cleaups and a small efficiency improvement to
this part of our swap handling code.

- "ptrace: introduce PTRACE_SET_SYSCALL_INFO API" from Dmitry Levin
adds the ability for a ptracer to modify syscalls arguments. At this
time we can alter only "system call information that are used by
strace system call tampering, namely, syscall number, syscall
arguments, and syscall return value.

This series should have been incorporated into mm.git's "non-MM"
branch, but I goofed.

- "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions" from
Andrei Vagin extends the info returned by the PAGEMAP_SCAN ioctl
against /proc/pid/pagemap. This permits CRIU to more efficiently get
at the info about guard regions.

- "Fix parameter passed to page_mapcount_is_type()" from Gavin Shan
implements that fix. No runtime effect is expected because
validate_page_before_insert() happens to fix up this error.

- "kernel/events/uprobes: uprobe_write_opcode() rewrite" from David
Hildenbrand basically brings uprobe text poking into the current
decade. Remove a bunch of hand-rolled implementation in favor of
using more current facilities.

- "mm/ptdump: Drop assumption that pxd_val() is u64" from Anshuman
Khandual provides enhancements and generalizations to the pte dumping
code. This might be needed when 128-bit Page Table Descriptors are
enabled for ARM.

- "Always call constructor for kernel page tables" from Kevin Brodsky
ensures that the ctor/dtor is always called for kernel pgtables, as
it already is for user pgtables.

This permits the addition of more functionality such as "insert hooks
to protect page tables". This change does result in various
architectures performing unnecesary work, but this is fixed up where
it is anticipated to occur.

- "Rust support for mm_struct, vm_area_struct, and mmap" from Alice
Ryhl adds plumbing to permit Rust access to core MM structures.

- "fix incorrectly disallowed anonymous VMA merges" from Lorenzo
Stoakes takes advantage of some VMA merging opportunities which we've
been missing for 15 years.

- "mm/madvise: batch tlb flushes for MADV_DONTNEED and MADV_FREE" from
SeongJae Park optimizes process_madvise()'s TLB flushing.

Instead of flushing each address range in the provided iovec, we
batch the flushing across all the iovec entries. The syscall's cost
was approximately halved with a microbenchmark which was designed to
load this particular operation.

- "Track node vacancy to reduce worst case allocation counts" from
Sidhartha Kumar makes the maple tree smarter about its node
preallocation.

stress-ng mmap performance increased by single-digit percentages and
the amount of unnecessarily preallocated memory was dramaticelly
reduced.

- "mm/gup: Minor fix, cleanup and improvements" from Baoquan He removes
a few unnecessary things which Baoquan noted when reading the code.

- ""Enhance sysfs handling for memory hotplug in weighted interleave"
from Rakie Kim "enhances the weighted interleave policy in the memory
management subsystem by improving sysfs handling, fixing memory
leaks, and introducing dynamic sysfs updates for memory hotplug
support". Fixes things on error paths which we are unlikely to hit.

- "mm/damon: auto-tune DAMOS for NUMA setups including tiered memory"
from SeongJae Park introduces new DAMOS quota goal metrics which
eliminate the manual tuning which is required when utilizing DAMON
for memory tiering.

- "mm/vmalloc.c: code cleanup and improvements" from Baoquan He
provides cleanups and small efficiency improvements which Baoquan
found via code inspection.

- "vmscan: enforce mems_effective during demotion" from Gregory Price
changes reclaim to respect cpuset.mems_effective during demotion when
possible. because presently, reclaim explicitly ignores
cpuset.mems_effective when demoting, which may cause the cpuset
settings to violated.

This is useful for isolating workloads on a multi-tenant system from
certain classes of memory more consistently.

- "Clean up split_huge_pmd_locked() and remove unnecessary folio
pointers" from Gavin Guo provides minor cleanups and efficiency gains
in in the huge page splitting and migrating code.

- "Use kmem_cache for memcg alloc" from Huan Yang creates a slab cache
for `struct mem_cgroup', yielding improved memory utilization.

- "add max arg to swappiness in memory.reclaim and lru_gen" from
Zhongkun He adds a new "max" argument to the "swappiness=" argument
for memory.reclaim MGLRU's lru_gen.

This directs proactive reclaim to reclaim from only anon folios
rather than file-backed folios.

- "kexec: introduce Kexec HandOver (KHO)" from Mike Rapoport is the
first step on the path to permitting the kernel to maintain existing
VMs while replacing the host kernel via file-based kexec. At this
time only memblock's reserve_mem is preserved.

- "mm: Introduce for_each_valid_pfn()" from David Woodhouse provides
and uses a smarter way of looping over a pfn range. By skipping
ranges of invalid pfns.

- "sched/numa: Skip VMA scanning on memory pinned to one NUMA node via
cpuset.mems" from Libo Chen removes a lot of pointless VMA scanning
when a task is pinned a single NUMA mode.

Dramatic performance benefits were seen in some real world cases.

- "JFS: Implement migrate_folio for jfs_metapage_aops" from Shivank
Garg addresses a warning which occurs during memory compaction when
using JFS.

- "move all VMA allocation, freeing and duplication logic to mm" from
Lorenzo Stoakes moves some VMA code from kernel/fork.c into the more
appropriate mm/vma.c.

- "mm, swap: clean up swap cache mapping helper" from Kairui Song
provides code consolidation and cleanups related to the folio_index()
function.

- "mm/gup: Cleanup memfd_pin_folios()" from Vishal Moola does that.

- "memcg: Fix test_memcg_min/low test failures" from Waiman Long
addresses some bogus failures which are being reported by the
test_memcontrol selftest.

- "eliminate mmap() retry merge, add .mmap_prepare hook" from Lorenzo
Stoakes commences the deprecation of file_operations.mmap() in favor
of the new file_operations.mmap_prepare().

The latter is more restrictive and prevents drivers from messing with
things in ways which, amongst other problems, may defeat VMA merging.

- "memcg: decouple memcg and objcg stocks"" from Shakeel Butt decouples
the per-cpu memcg charge cache from the objcg's one.

This is a step along the way to making memcg and objcg charging
NMI-safe, which is a BPF requirement.

- "mm/damon: minor fixups and improvements for code, tests, and
documents" from SeongJae Park is yet another batch of miscellaneous
DAMON changes. Fix and improve minor problems in code, tests and
documents.

- "memcg: make memcg stats irq safe" from Shakeel Butt converts memcg
stats to be irq safe. Another step along the way to making memcg
charging and stats updates NMI-safe, a BPF requirement.

- "Let unmap_hugepage_range() and several related functions take folio
instead of page" from Fan Ni provides folio conversions in the
hugetlb code.

* tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (285 commits)
mm: pcp: increase pcp->free_count threshold to trigger free_high
mm/hugetlb: convert use of struct page to folio in __unmap_hugepage_range()
mm/hugetlb: refactor __unmap_hugepage_range() to take folio instead of page
mm/hugetlb: refactor unmap_hugepage_range() to take folio instead of page
mm/hugetlb: pass folio instead of page to unmap_ref_private()
memcg: objcg stock trylock without irq disabling
memcg: no stock lock for cpu hot-unplug
memcg: make __mod_memcg_lruvec_state re-entrant safe against irqs
memcg: make count_memcg_events re-entrant safe against irqs
memcg: make mod_memcg_state re-entrant safe against irqs
memcg: move preempt disable to callers of memcg_rstat_updated
memcg: memcg_rstat_updated re-entrant safe against irqs
mm: khugepaged: decouple SHMEM and file folios' collapse
selftests/eventfd: correct test name and improve messages
alloc_tag: check mem_profiling_support in alloc_tag_init
Docs/damon: update titles and brief introductions to explain DAMOS
selftests/damon/_damon_sysfs: read tried regions directories in order
mm/damon/tests/core-kunit: add a test for damos_set_filters_default_reject()
mm/damon/paddr: remove unused variable, folio_list, in damon_pa_stat()
mm/damon/sysfs-schemes: fix wrong comment on damons_sysfs_quota_goal_metric_strs
...

Merge branch 'x86/nmi' into x86/core, to merge dependent commits

2025-05-13T08:46:04+00:00

Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:

  6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Signed-off-by: Ingo Molnar

x86/kexec: add support for passing kexec handover (KHO) data

2025-05-13T06:50:41+00:00

kexec handover (KHO) creates a metadata that the kernels pass between each
other during kexec.  This metadata is stored in memory and kexec image
contains a (physical) pointer to that memory.

In addition, KHO keeps "scratch regions" available for kexec: physically
contiguous memory regions that are guaranteed to not have any memory that
KHO would preserve.  The new kernel bootstraps itself using the scratch
regions and sets all handed over memory as in use.  When subsystems that
support KHO initialize, they introspect the KHO metadata, restore
preserved memory regions, and retrieve their state stored in the preserved
memory.

Enlighten x86 kexec-file and boot path about the KHO metadata and make
sure it gets passed along to the next kernel.

Link: https://lkml.kernel.org/r/20250509074635.3187114-12-changyuanl@google.com
Signed-off-by: Alexander Graf 
Co-developed-by: Mike Rapoport (Microsoft) 
Signed-off-by: Mike Rapoport (Microsoft) 
Co-developed-by: Changyuan Lyu 
Signed-off-by: Changyuan Lyu 
Acked-by: Dave Hansen 
Cc: Andy Lutomirski 
Cc: Anthony Yznaga 
Cc: Arnd Bergmann 
Cc: Ashish Kalra 
Cc: Ben Herrenschmidt 
Cc: Borislav Betkov 
Cc: Catalin Marinas 
Cc: David Woodhouse 
Cc: Eric Biederman 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: James Gowans 
Cc: Jason Gunthorpe 
Cc: Jonathan Corbet 
Cc: Krzysztof Kozlowski 
Cc: Marc Rutland 
Cc: Paolo Bonzini 
Cc: Pasha Tatashin 
Cc: Peter Zijlstra 
Cc: Pratyush Yadav 
Cc: Rob Herring 
Cc: Saravana Kannan 
Cc: Stanislav Kinsburskii 
Cc: Steven Rostedt 
Cc: Thomas Gleinxer 
Cc: Thomas Lendacky 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

x86/setup: use memblock_reserve_kern for memory used by kernel

2025-05-13T06:50:41+00:00

memblock_reserve() does not distinguish memory used by firmware from
memory used by kernel.

The distinction is nice to have for accounting of early memory allocations
and reservations, but it is essential for kexec handover (kho) to know how
much memory kernel consumes during boot.

Use memblock_reserve_kern() to reserve kernel memory, such as kernel
image, initrd and setup data.

Link: https://lkml.kernel.org/r/20250509074635.3187114-11-changyuanl@google.com
Signed-off-by: Mike Rapoport (Microsoft) 
Signed-off-by: Changyuan Lyu 
Acked-by: Dave Hansen 
Cc: Alexander Graf 
Cc: Andy Lutomirski 
Cc: Anthony Yznaga 
Cc: Arnd Bergmann 
Cc: Ashish Kalra 
Cc: Ben Herrenschmidt 
Cc: Borislav Betkov 
Cc: Catalin Marinas 
Cc: David Woodhouse 
Cc: Eric Biederman 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: James Gowans 
Cc: Jason Gunthorpe 
Cc: Jonathan Corbet 
Cc: Krzysztof Kozlowski 
Cc: Marc Rutland 
Cc: Paolo Bonzini 
Cc: Pasha Tatashin 
Cc: Peter Zijlstra 
Cc: Pratyush Yadav 
Cc: Rob Herring 
Cc: Saravana Kannan 
Cc: Stanislav Kinsburskii 
Cc: Steven Rostedt 
Cc: Thomas Gleinxer 
Cc: Thomas Lendacky 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

x86/boot: Add a bunch of PIC aliases

2025-05-04T13:59:43+00:00

Add aliases for all the data objects that the startup code references -
this is needed so that this code can be moved into its own confined area
where it can only access symbols that have a __pi_ prefix.

Signed-off-by: Ard Biesheuvel 
Signed-off-by: Ingo Molnar 
Cc: Arnd Bergmann 
Cc: David Woodhouse 
Cc: Dionna Amalie Glaze 
Cc: H. Peter Anvin 
Cc: Kees Cook 
Cc: Kevin Loughlin 
Cc: Len Brown 
Cc: Linus Torvalds 
Cc: Rafael J. Wysocki 
Cc: Tom Lendacky 
Cc: linux-efi@vger.kernel.org
Link: https://lore.kernel.org/r/20250504095230.2932860-39-ardb+git@google.com